Draw-works brake



April 28, 1931. L. ca. GATES DRAW WORKS BRAKE Filed May 20, 1930 mill.

INVENTOR fats ATTORNEYS.

Patented Apr. 28, 1931 UNITE LEROY G. GATES, OF BAKERSFIELD, CALIFORNIADRAVV-WORKS BRAKE Application filed May 20,

The present invention relates to friction brakes especially adapted forhoisting apparatus. It is described herein as applied to the draw-worksof an oil well rig, but its ready adaptation to other forms of apparatuswill be apparent to those skilled in the art.

The principal objects of the invention are to provide an adjustablebrake which is easy apply, and which is not subject to kickback of theoperating lever upon reversal of the drum, and which cannot be loosenedor rendered less effective by such reversal. Other objects andadvantages of the invention will be apparent from the followingdescription, which should be read with the understanding that the form,construction and arrangement of the several parts may be varied withinthe limits of the claims hereto appended, without departing from thespirit of the invention as set forth therein.

The invention will now be described fully with reference to theaccompanying drawings, wherein Fig. 1 is a part sectional side elevationof a simple form of brake embodying the principles of my invention.

Fig. 2 is a horizontal section taken on the line 22 of Fig. 1.

Fig. 3v is a side elevation showing a modification of one feature of theinvention.

Fig. 4 is a detail, partly in section, of the rollers indicated in Fig.3;

Fig. 5 is a diagrammatic detail showing a further modification of theform of device shown in Fig. 3.

My invention belongs to the type of brakes in which friction isintroduced into the movement of the operating mechanism, to assist theleverage of said mechanism in resisting reaction of the braking member,i. e. in preventing kick-back. In the simple form of constructionillustrated in Fig. 1, this friction is present while the brake is 1930.Serial N6. 453,977.

being applied as well as while it is being re-. leased, and results,naturally, in a certain loss of power in the operating mechanism. Thisformof device is suitable in situations where the maximum necessarybraking effect can be produced with the power available (assumed to bethe muscular effort of one man) even with the loss of efficiency due tothe inherent friction of the operating mechanism. But in modern deepwell drilling, the loads handled by the draw-works are so great that thebrake, in order to be effective and still be within the ability of oneman to operate, must have the maximum ehiciency possible. In such casesI prefer the form of device shown in Figs. 3 and 4:, in which thefriction in the operating mechanism is applied only during the releasingof the brake, and is relieved during the applicat-ion thereof. In otherwords, the movement of the operating mechanism is free when applying thebrake, but is frictionally impeded during its release. Therefore, theelement of safety against kickback is retained, without the loss ofpower or efficiency inherent in the first form of construction. Both themeans by which friction is applied to the operating mechanism and thebraking members themselves may be of any suitable types. I have shown,in both forms of my device, for the sake of illustration, a band type ofbrake applied to a rotating drum, and a slidable wedge for tighteningthe band about said drum. In this type of operating mechanism, thefriction between the wedge and the member upon which it slidesintroduces the desired impedance into the operating mechanism.

Referring for the present to Figs. 1 and 2 of the drawings, thereference numeral 6 designates a rotating drum to which the brake isapplied, and may be considered, for example, as secured to or formed asa :part of the usual drawrworks drum. It is surrounded by a band 7, oneend of which is anchored to a fixed member 8. The other end of said bandis adjustably secured to a U-shaped horizontal yoke 9 by means of across piece 10 and nuts 11, the latter threaded upon the legs of theyoke 9.

The fixed member 8, which is straddled by the yoke 9, has an inclinedface 12, Fig. 1, upon which slides a wedge block 13. A roller 14,mounted in the yoke 9, bears against the outer face 15 of the wedge 13,so that, as said wedge is moved down, the yoke is shifted to the left,thereby tightening the band Tabout the drum 6; The yoke 9 has anextension 16, which slides in a fixed guide member 17 to preventvertical movement, and a suitable spring may be provided,

as indicated at 18, to keep the roller. 14: in

contact with the wedge 13. An operating lever 19, fulcrumed at 20, isconnected with the wedge 13 in any suitable manner, aszby an arm 21' andlink 22.

The major portion of the face 15 of the wedge 13 lies substantially atright angles to the direction of movement of the yoke 9, so thatdownward thrust upon the yoke, in applying the brake, is reduced to aminimum. The lower portion 15 of said face is preferably inclined, asshown, so that the initial movement of the wedge takes up the band morerapidly than the final portion. The adjusting nuts 11 are so set thatthe band does not grip the drum until the roller 1% begins to ride uponthe vertical wedge.

face portion 15.

It will be seen that with the brake applied and the drum 6 rotating ina, clockwise direction, there is comparatively little pull on the yoke9, but whensaid'drum reverses its rotation, the pull on said'yokeisgreatly increased. However, by properly designin the angle between thewedge face 12 and the direction of movement of the yoke, it is possibleto prevent such increased pull from being transmitted to the lever 19,i. e. to prevent a kick-back, which might be dangerous to the operator.I have found that if the tangent of the angle between the faces 12 and15 (assuming the face 15 to .be perpendicular to the direction ofmovement ofth yoke) is equal'to thecoefiicient of friction between thewedge 13 and the stationary member 8, there is no danger of kick-back.

The above described simple construction. asillustrated in Fig. 1, issuitablewhen the normal rotation of the drum is clockwise, and when thebraking load is moderate. The brake requires considerable. effort toapply, because of the friction between the wedge and the face 12 of themember 8, but if the drum reverses while the brake is applied, noadditional strain is placed upon the lever 19' or the operator holdingit. However, if the normal braking load is *very heavy, or if it isdesired to apply the brake while the drum is rotating counterclockwise,the increased efl'ort required to apply the brake may well be beyond thecapacity of the operator. In such cases, I prefer the construction shownin Figs. 3 and 4.

In this construction, the principal elements are the same as describedabove, except that the fixed member 8, instead of having a flat surfaceupon which the wedge 13 slides, is provided with a plurality of rollers23, upon which the face 12 of said wedge rolls. These rollers areprovided with suitable means for locking them against rotation in onedirection. As an example of such means, I have shown, in Fig. l, aratchet. clutch mechanism comprising an annular flange 24lformed uponthe end of the roller 23, and a fixed clutch member 25 positioned withinsaid flange and provided with cam faces 26. Floating rollers 27 areinterposed between the flange 24 and said cam faces, so that they jamwhen the roller 28 attempts to turn in a clockwise direction, i. e. whenthe wedge 13 moves upwardly, and thus prevent said roller 23 fromturning. It turns freely, however, in a counter-clockwise direction. Theclutch member 25 may be secured to or formed as a part of the side '8"of the fixed support 8 in which the rollers 23 are mounted. Each of saidrollers is understood to be equipped with similar locking mechanisnnor,if desired, only one-or two rollers may be provided with a lockingmechanism,. and the entire series inclosedv by an endless chain or belt,as indicated at 28, in Fig.- 5, against which the wedge face 12 bears.

It will readily be seen that in the form of" device shown in Figs. 3, 4andx5, there is practically no friction to retard'thedownward. movementof the. wedge 13,. so that the maximum efliciency of the operatingmechanism is available in applying the brake,.but if the drum reverses,the friction between the wedge and the locked rollers 23 (or the belt orchain 28 of Fig. 5-) operates to prevent upward movement of said wedgedue to the increased pull'of; the band,- i..e. kick-backis preventedjust as effectually as in the form of device shown in Fig. 1. Thislatter effect is assured, as. before, by making the tangent'ofthe anglebetween the wedge faces 12' and 15 equal to the coefficient of frictionbetweenthe wedge and-the; locked rollers 23 (or the belt or chain 28 ofFig. 5). The face 15 is preferably substantially at ri'ght angles tothe'yoke. or tensionmemher 9, as in the form of device shownin Fig. 1.

Thus, it willb'e readily understood, the movement of the operatingmechanismis impeded, by friction, in; all forms ofmy invention, upon thereleasing of the brake,

so that the danger of-kick-backupon reverlit) sal of the drum iseliminated. This friction also operates, in the form shown in Fig. l, toimpede the operating mechanism in applying the brake, but in the formshown in Fig. 3 there is no impedance to the applying force, and themaximum braking effort can be secured.

I claim 1. A brake comprising a moving member; a retarding member; anoperating member connected with said retarding member for moving it intocontact with said moving member; a wedge having one face bearing againstsaid operating member and movable transversely thereof; a supportagainst which the other face of said wedge bears; and means fordecreasing the friction between said Wedge and said support in onedirection of movement.

2. A brake comprising a moving member; a retarding member; an operatingmember connected with said retarding member for moving it into contactwith said moving member; a wedge having one facebearing against saidoperating member and movable transversely thereof; a support forreceiving the thrust of the other face of said wedge; and means forimpeding the movement of said wedge in one direction.

3. A brake comprising a moving member; a retarding member; an operatingmember connected with said retarding member for moving it into contactwith said moving member; a wedge having one face bearing against saidoperating member and movable transversely thereof; a support; a rollermounted thereon for receiving the thrust of the other face of saidwedge; and means for impeding the rotation of said roller in onedirection.

4. A brake comprising a moving member; retarding member; an operatingmember connected with said retarding member for moving it into contactwith said moving member; a wedge having one face bearing against saidoperating member and movable transversely thereof; a support; a rollermounted thereon for receiving the thrust of the other face of saidwedge; and a ratchet mechanism for impeding rotation of said roller inone direction.

5. A brake comprising a moving member; a retarding member; a wedge formoving said retarding member into frictional contact with said movingmember; a support movable with said wedge in one direction for receivingthe thrust thereof; and means for impeding the movement of said supportin the other direction.

6. A brake comprising a moving member; a retarding member; mechanism formoving said retarding member into and out of frictional contact withsaid moving member;

and means for frictionally impeding the

